Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Mineralogical Magazine Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Mineralogical Magazine; April 2008; v. 72; no. 2; p. 667-681; DOI: 10.1180/minmag.2008.072.2.667
© 2008 Mineralogical Society of Great Britain and Ireland
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Pokrovski, G. S.
Right arrow Articles by Lemeshko, M. P.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

In situ X-ray absorption spectroscopy measurement of vapour-brine fractionation of antimony at hydrothermal conditions

G. S. Pokrovski1,*, J. Roux2, J.-L. Hazemann3, A. Yu. Borisova1,4, A. A. Gonchar5 and M. P. Lemeshko6

1 Experimental Geochemistry and Biogeochemistry Group, LMTG - Université de Toulouse - CNRS - IRD - OMP, Laboratoire des Mécanismes et Transferts en Géologie, 14 Av. E. Belin, F-31400 Toulouse, France
2 Equipe PMM - Institut de Physique du Globe de Paris, 4 Place Jussieu, F-75252 Paris, cedex 05, France
3 Institut Néel, CNRS, 25 avenue des Martyrs, 38042 Grenoble Cedex 9, France
4 Geological Department, Moscow State University, Moscow, Russia
5 Department of Chemical Physics, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany
6 Department of Molecular Physics, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany

* E-mail: pokrovsk{at}lmtg.obs-mip.fr

Despite the growing geological evidence that fluid boiling and vapour-liquid separation affect the distribution of metals in magmatic-hydrothermal systems significantly, there are few experimental data on the chemical status and partitioning of metals in the vapour and liquid phases. Here we report on an in situ measurement, using X-ray absorption fine structure (XAFS) spectroscopy, of antimony speciation and partitioning in the system Sb2O3-H2O-NaCl-HCl at 400°C and pressures 270–300 bar corresponding to the vapour-liquid equilibrium. Experiments were performed using a spectroscopic cell which allows simultaneous determination of the total concentration and atomic environment of the absorbing element (Sb) in each phase. Results show that quantitative vapour-brine separation of a supercritical aqueous salt fluid can be achieved by a controlled decompression and monitoring the X-ray absorbance of the fluid phase. Antimony concentrations in equilibrium with Sb2O3 (cubic, senarmontite) in the coexisting vapour and liquid phases and corresponding SbIII vapour-liquid partitioning coefficients are in agreement with recent data obtained using batch-reactor solubility techniques. The XAFS spectra analysis shows that hydroxy-chloride complexes, probably Sb(OH)2Cl0, are dominant both in the vapour and liquid phase in a salt-water system at acidic conditions. This first in situ XAFS study of element fractionation between coexisting volatile and dense phases opens new possibilities for systematic investigations of vapour-brine and fluid-melt immiscibility phenomena, avoiding many experimental artifacts common in less direct techniques.

KEYWORDS: antimony, X-ray absorption spectroscopy, vapour-liquid fractionation, Sb hydroxy-chloride complexes, H2O-NaCl system, magmatic-hydrothermal deposit






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Mineralogical Society of Great Britain and Ireland